% !Mode:: "TeX:UTF-8"%確保文檔utf-8編碼
\documentclass[tikz,border=2pt]{standalone}
\usepackage{pgfplots}
\pgfplotsset{compat=newest}
\usetikzlibrary{positioning,calc}
\begin{document}
\begin{tikzpicture}
\node[right] (a)  {test};
\node[right] (b) [above right = of a] {test};
\node[right] (b0) [below right = of a] {test};
\coordinate (amidb) at ($(a)!0.5!(a -| b)$);

\draw[->] (a) -- (amidb) |- (b.west) ;
\draw[->]  (amidb)  |- (b0.west);


\node[right] (c) [above right = of b0] {test};
\node[right] (c0) [below right = of b0] {test};
\coordinate (b0midc) at ($(b0)!0.5!(b0 -| c)$);

\draw[->] (b0) -- (b0midc) |- (c.west) ;
\draw[->]  (b0midc)  |- (c0.west);
\end{tikzpicture}
\end{document}